Pneumatic separator for pulverulent materials



Jan. 7, 1964 H. c. KIRKHAM 3,117,081

PNEUMATIC SEPARATOR FOR PULVERULENT MATERIALS Filed July 17, 1961 ZSheets-Sheet 1 HO /22 A24 Howard CKirkh'czm INVENTOR.

Fig-.1. Mid mm Hffys.

Jan. 7, 1964 H. c. KIRKHAM 3,117,081

PNEUMATIC SEPARATOR FOR PULVERULENT MATERIALS Filed July 17, 1961 2 Sheets-Sheet 2 Howard C. Kirkham INVENTOR.

United States Patent 3,117,081 PNEUMATIC SEPARATOR FOR PULVERULENT MATERIALS Howard C. Kirkham, 412 SW. 17th St., Pendleton, Oreg. Filed July 17, 1961, Ser. No. 124,434 Claims. (Cl. 209-12) This invention relates to particle separation, and more particularly to a means for separating particle matter into coarse and fine fractions, or into .dense and less dense fractions where the particle size is substantially the same. The invention relies upon the gravity flow of material toward the base of a separating chamber, with the dispersion of such material in a swirling current of air so that the material arranges itself in a vertically downwardly extending annular zone. Air drawn in through the zone is effective to remove air-suspendable particles, and nonair-suspendable particles collect at the base of the chamber. Features of the invention include good mixing of air with the particle matter during the separation process, and versatility with respect to the ranges of particle sizes and weights that can be processed. All this is obtained with a relatively simple construction, and without the use of the complex parts that characterize machines known .to date.

The invention has particular utility in connection with the separation of pulverized grain into fractions such as flour of desired fineness, coarse middlings, and particles having a size less than that desired, such particles being referred to sometimes as dust or fines.

In the past, commercial flour was relatively coarse, and the separation of flour from pulverized grain material was easily done by passing the material through relatively coarse sifting cloths, with all that passed through the cloths being sold as flour. With the increase in the demand for finer flour, such as is used in cakes, fine silk screens have been used to sift flour, but such have produced problems as their capacity is limited. 'Theseproblems have intensified with impact grinding techniques becoming popular, as such produce a greater proportion of fine flour, and silk screens have not been able etiiciently to handle-the greater output of 'fine flour. 'The apparatus of this invention may be used to alleviate the bottleneck previously existing at the silk screens, as it enablepulvenilent materials, such as pulverized grain,.to be sepa rated expeditiously into. fractions of desired fineness, ,withouthaving to rely on screen-type sifting. While the invention is described primarily in connection with the processing of a pulverized, grain productyit shouldbe obvious that it has applicability in other separations, where problems. involved are. similar.

Thus, a generalobject of-the--invention is to provide an improved app aratus. for. separatingxa pulverulent product into various fractions, the apparatus beingdevoid of screen-type sifting devices, that :relies on centrifugal and gravity forces, and a novel form of air currents, for effecting separation.

Another general object 1 is .tovprovide an 7 improved apparatus for processing a:milled.grain productaintol-fractions of desired particle size and density.

A more specificaobject is to PIOVldB'IHOVfil apparatus for separating particles into various" fractions, where one stage of the separation performedin the apparatus-relies uponithe dispersion 'of:.particles into anxannular zone,

zone. The apparatus features'a separating chamber, with an upperextension in the formof an annulus where air 3,117,081 Patented Jan. 7, 1864- is induced to flow in a circular path as particles drop through the upper extension, and below the extension a base portion, .the latter communicating with the base of a passage through which air travels on leaving the separating chamber.

Another object of the invention is to provide novel apparatus for separating particles that includes a unique organization of valve-controlled air flow passages, that results in more versatility in handling different size and weight ranges of particles than in previous structures. As an example, variations may'easily be made in theamount of air that is recirculated in the system, and the amount of air that passes through the annular zone described above, with different types of separation resulting.

Another object is :to provide apparatus for separating particles that includes several'fan chambers, with motordriven fans therein, where the apparatus is constructed so that a drive mechanism for the fans may be provided that is efficient and relatively uncomplicated.

These and other objects and advantages are attained by the invention, and the same is described hereinbelow in conjunction with the accompanying drawings, wherein:

FIG. 1 isa side elevation of apparatus according to an embodiment of the invention, with portions of the apparatus removed, and in section, in order better to illustrate details ofinterior construction;

FIG. 2 is a top plan view of the apparatus in FIG. 1;

FIG. 3 is a cross-sectional view, taken generally along the line 33 in FIG. 1;

FIG. 4 is a cross-sectionalview, taken generally along the line 44 in FIG, 1, and showing portions of a valve mechanism or means in the construction; and

FIG. 5 is a cross-sectional view, taken along the line -5--5 in FIG. 1, showing, in plan, a fan in the apparatus.

Referring now to the drawings, andmore particularly to FIG. 1, apparatus constructed according to the invention comprises a framework, generally indicated-at Y10, and within and supported by framework 10 a casing structure, generally indicated at 1 2. Atthe-right of FIG. 1, the casing structure isprovided with walls that define a series of chambers, indicated .at .20, 22, '24, and 26, stacked one over anotherprogressing upwardly --from the base of the structure. These chambers are herein referred to asa separating chambenza first fan chamber, a second fan chamber, and a fan intake chamber, respecvtively.

More specifically, and with reference to separating chamber 20, at the base of the casing structure a wall 363 that curves about a vertical central axis 32 (and is substantially cylindrical) defines the outer boundary of a .bottomportionztla of separating chamber zil. A conical floor 31 closes off -the 'base of ;portion-2ila. Above Wall fitlthat defines ;bottom;portion 20ais,a frusto-conicalwall 13.4, and afiQnduit ortube -36 of round-crosssection. Wall 134 and tube 36 are-concentric, and the-insideof wall34 iandthe outside of tube 36 define-an annular chamber iZilb extendingcircumferentially about axis 32. Charnber Zilb is an upper portion or extension of portion 20a of the separating chamber, and communicates continuously about its-basewvith gthe top of bottom portion 20a.

Thejinside of tube 36 defines an upright passage .38 that communicates at i-tsbase ,with ehamber zd-more specifically bottom -portion 2000f chamber'ltl.

First" fan chamber ,-22- disposed above annular chamber 20b has .substantially;a;roundcross section; and is defined -bya cylindrical .wall 49, that also curves about axis 32. Thus, the chamber is aligned vertically above separating chamber '20. The/top and bottom .of the chamber are closed off by.walls :42,J44. .A bore .46 inwall .44 .at the base of the chamber provides an inlet for fair chamber 22, and an aperture.:48 in cylindrical wall 40 provides.- an

3 outlet in the circumferential periphery of the fan chamber.

Between fan chamber 22 and the top of tube 36 defining passage 38 is a valve mechanism, generally indicated at 50. Referring to FIGS. 1 and 4, mechanism 50 is enclosed in a valve chamber 53, the outer boundary of which is defined by a cylindrical wall 52. Bore 46 in wall 44 (the inlet for fan chamber 22) connects chamber 53 with the fan chamber. A wall 59 closes off the top of annular chamber 20b, and a bore 60 in wall 59 connects the base of chamber 53 and the top of passage 38.

Valve mechanism 50 comprises a plate 64 mounted in fixed position within the valve chamber, having ports 66 extending therethrough (see FIG. 4). Rotatably mounted over the top side of plate 64, for movement about axis 32, is an adjustable plate 68, with ports 70 therein. Ports 70 are movable to varying degrees of registry with ports 66, by proper adjustment of plate 68. A handle 72 provides a means for adjusting plate 68 by rotating it. Valve mechanism 50 constitutes a means for controlling the flow of air from passage 38 into fan chamber 22.

Another inlet, for outside air, is provided at the top of fan chamber 22. Thus, ports 76 extend axially through wall 42 adjacent the center of wall 42. Resting on the top of wall 42 is an adjustable valve plate 73. Plate 78 is rotatable about axis 32, and contains ports 79 movable into various degrees of reigstry with ports 76. Plate 78 constitutes a valve means in the construction controlling the flow of air from the outside into the top of the fan chamber, through the inlet provided by ports 76.

Material to be processed is fed into the upper end of annular chamber or extension 2% through a chute 80. This material then falls downwardly toward floor 31 of separating chamber 20. As will become hereinafter apparent, means is provided adjacent the base of bottom portion 20a of the separating chamber for producing a swirling current of air, with such air moving in a circular path about axis 32. Material as it drops in the upper portion of the separating chamber is dispersed in an annular zone that extends approximately vertically downwardly toward floor 31. The slope selected for floor 31 aids in the production of the swirling air current desired.

A conduit or spout 86 extending downwardly from floor 31 adjacent its outer margin is provided for the collection and removal of nonair-suspendable material, after such travels to the base of the separating chamber.

To the left of easing structure 12 defining chambers 20 and 22 in FIG. 1 is additional casing structure 90, with walls 93, 94 defining a second separating chamber 92. Chamber 92, as shown, is part of a cyclone separator, and thus wall 94, defining the top of the chamber, is cylindrical, and wall 93, defining the bottom of the chamber, is conically tapered.

Aperture 48 (the outlet of the fan chamber 22) is connected to the top and circumferential periphery of separating chamber 92 by a duct or conduit means 100 that opens to the interior of the separating chamber through an aperture 102 in wall 94. Duct 100 curves in plan, as best illustrated in FIG. 2, so that when air and suspended material moves from right to left in FIG. 2, the same enters chamber 92 with a swirling current of air produced within the chamber.

In separating chamber 92, heavier particles are thrown outwardly by centrifugal force to the periphery of the chamber, and eventually fall by gravity to the base of the chamber whence they are removed through a conduit or spout 104. Extending into the interior of chamber 92 from the top is a duct or conduit means 106, and as will hereinafter be apparent, during operation of the apparatus air is sucked up through this duct. In the cyclone separator, subatmospheric pressures are produced in the center thereof, causing lighter particles to migrate to the center, whence they are drawn by a current of air upwardly into duct 106.

Duct 106 is connected to fan intake chamber 26 by a duct 107. Between adjacent ends of ducts 106, 107 is a valve mechanism 110. This mechanism is similar to mechanism 50 already described, and includes a fixed plate 118 within the mechanism containing bores (not shown) and a rotatable plate 122 mounted above plate 118 with bores 124 therein that may be adjusted to varying degrees of registry with the bores of plate 118.

Considering now the construction of second fan chamber 24 and fan intake chamber 26, these are round in cross section, and their circumferential peripheries are defined by a cylindrical wall 130. Top and bottom walls 132, 134 close off the top and bottom of chambers 26, 24, respectively. Intermediate walls 132, 134 is a divider wall 136, with a central bore 138 therein. Wall 136 de fines the lower end of chamber 26 and the upper end of chamber 24, these two chambers communicating with each other through bore 138. The entire structure is supported on the top of the structure defining first fan chamber 22 by legs 140.

Bore 133 constitutes an inlet for the second fan chamber and ducts 106, 107 connect with this inlet through the fan intake chamber. An inlet for outside air is provided the fan intake chamber, such taking the form of a port 144 opened and closed by a valve 146.

An aperture 150 in wall 130 defining the second fan chamber provides an outlet in the circumferential periphcry of the chamber, and such is connected by a duct or conduit means 152 with an elongated duct or conduit 156. Duct 156 has a top end, that may be connected to the usual dust collector (not shown). With reference to FIGS. 1 and 3, the base of duct 156 connects with a circular chamber 158 defined by a wall 160 that is about the outside of and concentric with wall 34. An annular wall 162 with ports 164 circumterentially spaced thereabout is at the base of chamber 158. The ports accommodate the flow of air from chamber 158 into the top of bottom portion 20a of the separating chamber, from locations spaced about the outside of annular chamber or extension 2012.

Duct or conduit means 156 is provided with a valve 166 that may be adjusted to direct air traveling from the second fan chamber either up through the top end thereof, or to direct all or part of such air downwardly to the base of duct 156. In the latter instance, there is recirculation of air within the apparatus. Outside air may be admitted to the base of duct 156 through a port 167 regulated by valve 168.

The various tan chambers, and bottom separating chamber 20, are provided with motor-driven means or mechanisms producing movement of air therein. Thus, extending vertically in the apparatus, substantially long axis 32, is an elongated power-driven shaft 170. Bearing stnucture 172 supports the base of the shaft, and the top of the shaft is driven by a motor, such as electric motor 174. Secured to the shafit, and within second fan chamber 24, is a blower or fan 176. Secured to the shaft below fan 176 and within the first fan chamber is a blower or fan 178 (shown in plan in FIG. 5). Adjacent the base of the shaft, and mounted separating chamber 20, is a fan 180.

In the construction described, upon energizing motor 174, the various fans are driven in the same direction, which is a counterclockwise direction in FIG. 5, as shown by the arrow in FIG. 5. When rotated in this manner, {fans 176, 178 are operable to suck air axially into their centers, and expel it circumferentially through the outlets and 'ducts described. Fan "180 in the separating chamber is operable to produce a swirling air current, with the air moving in a circular path in annular chamber 20b and about the outside of chamber 20a.

Describing now the operation of the apparatus in con nection with the separation of pulverized grain into fractions comprising -a coarse fraction or middlings (needing regrinding), a flour fraction, and a fraction of particles of less than desired size for flour (fines or dust), the

and a less dense fiber. or bran constituent.

pulverized grain is admitted to the apparatus through chute 80. Valves 166 and 168 typically may first be adjusted so that there is some degree of recirculation of air, and a certain portion of the air from fan chamber 24 passes out the top of duct 156 without being recirculated. The motor is energized to start movement of the various fans.

With actuation of the fans, circulated air travels in the direction of the arrows in FIG. 1. A suction is produced in the base of passage 38, and air is drawn up through the passage into the first fan chamber, whence it is expelled through the outlet of chamber 22 and duct 160 into second separating chamber 9'2. Air traveling up passage 38 first enters chamber 20 through ports 164, which are disposed to the outside of the base of annular chamber 20b. Because of the swirling movement of air produced by fan 180 in chamber 20, material as it cascades from chute 80, is dispersed into a downwardly extending annular zone. Air moves through this material, entirely about the zone, in traveling toward pasage 38, and in so doing is mixed with the material and is eltective to carry with it tfiour and fines. The heavier middling fraction is thrown outwardly by centrifugal force, and drops by gravity to the base of chamber 20 and thence into spout 86. Thus, by classification, the heavier fraction is removed.

Air together with suspended material (in this case flour and fines) upon reaching the cyclone separator (separating chamber 92) slows down somewhat in its movement, which enables the flour constituent of the suspended material to drop out of the air and collect at the base of chamber 92, whence it falls out of the chamher through spout 104. Because of the SllbfitlllOSPhGliC pressures existing at the center of chamber 2, and the movement of air upwardly through duct 106, the fine constituent of the material introduced to the cyclone chamber is drawn upwardly through ducts 1G6, 107, and

is carried by a current of into the fan inlet chamber and the second fan chamber. On leaving the second fan chamber, a certain fraction of the air and the fines therein may be expelled through the top of conduit 156, and the remainder recirculated through the bottom of conduit 156.

Using the apparatus of the invention in the manner described, pulverized grain may be processed directly, with the separation of flour therefrom, and without having to screen the material to remove coarse middlings, or material thatistoo fine, suchas dust or fines.

The apparatusmay-alsobe used'to separate ilourinto fractions containinga reltatively. dense starch constituent, In making such a separatiomall that is necessary is properly to adjust the velocities of the air currentsin the apparatus, using the various valve-means o-r mechanisms described. It has been found that flour of fairly uniform particle size contains a certain proportion of relatively dense starch material, and a certain proportion of less dense bran or fiber material, and this may be separated in separating chamber 249 by adjusting valves 50, '78, 166, and 168 so that the current of air passing up through passage 38 is sufiicint to carry with it only the less dense fiber or bran material. A larger opening of ports 76 (the inlet controlled by valve 78 for outside air to the top of fan chamber 22) results in a slower movement of air upwardly through passage 38. Valves 166, 168 also afiect the movement of air up through passage 38, by controlling the movement of air fed into separating chamber 20.

Valves 1 10 and 146 are used in the control of separating chamber 92, and the character of the material withdrawn through ducts 106, 107.

In addition to pulverized grain, the separating apparatus may be used in the separation of other particle material, such as certain dry chemicals and the like, into fractions according to size and weight of the particles. When it is desired to separate material into two fractions only, there 6 may be complete recirculation of air from Ifan chamber 24 to separating chamber 20. With three fractions to be collected, however, a certain amount of air containing the finest fraction collected should be bled oil through the top of conduit 156.

I claim:

1. Particle separating apparatus, comprising a separating chamber bounded by an outer wall that curves about a substantially upright central axis, means defining an upright passage disposed substantially along said axis that extends up from said chamber, feed means for feeding particle matter adjacent the top or said chamber and to one side of said passage with such matte-r falling by gravity downwardly in said chamber, power-driven means Within said separating chamber constructed to produce a swirling air current that moves about said axis with such current operable to distribute particle matter falling in said chamber .into a zone that extends downwardly in said chamber and circumferentially about said axis, means for drawing air up through said passage from the interior of said chamber, and means for admitting air to be drawn through said passage disposed outside the zone occupied by particle matter falling in said chamber.

2. Particle separating apparatus, comprising casing structure with walls defining an upright passage and adjacent the base ot said passage and communicating therewitha bottom chamber, said casing structurealso having walls defining an annular chamber above said bottom chamber and encircling said passage and connecting around substantially its entire-base with said bottom chamber, means within said bottom chamber for swirling air therein about the axis of said annular chamber and with such an the air in said annular chamber, means connecting with said annular chamber and adja- .cent the top thereof for feeding particle matter thereand means adjacent thebase and outside of saidannular chamber for admitting air to be drawn through said passage with such air passing through particle matter as it .falls from-said annular chamber into said bottomchamber.

3. The particle separating apparatus of claim 2, wherein the means for admitting air comprises means disposed substantially entirely around said annular chamber, whereby air is admitted from locations disposed around said chamber.

4. Particle separating apparatus, comprising casing .structure with walls defining an uprightpassage that is round in cross section and adjacent the base of said .passageand communicating therewith .a bottom chamber that is round in cross section and axiallyaligned with said passage, said bottom chamber having afloorof coni- .cal shape and around the=circurnferencethereof being bounded by a nonperfiorate wall, said casing structure also having walls defining an annular chamber above said bottom chamber and encircling said passage and connecting around substantially its entire base with said bottom chamber, said annular chamber around its inner and outer circumference being bounded by imperforate walls, means within said bottom chamber for swirling air therein about the axis of said annular chamber and with such air the air in said annular chamber, means connecting with said annular chamber and adjacent the top thereof for feeding panticle matter thereinto, means connecting with the floor of said bottom chamber adjacent its outer margin and accommodating the flow of particle matter out from said bottom chamber, means for drawing air upwardly through said passage from said bottom chamber, and means encircling said annular chamber communicating with said base chamber at locations distributed substantially entirely about said annular chamber for admitting air to be drawn through said passage with such air passing through particle matter as it falls from said annular chamber into the base chamber.

5. Particle separating apparatus, comprising casing structure with walls defining within the structure an elongated upright passage and at the base of said passage and communicating therewith the bottom portion of a separating chamber, said separating chamber having an upper portion of annular shape that is an extension of said bottom portion and encircles said passage, a fan rotatable about the axis of said passage mounted adjacent the base of said separating chamber and constructed to produce an air current in said extension and bottom portions of the separating chamber with such air moving about the axis of said passage, means connecting with said extension adjacent the top thereof for feeding particle matter thereto, and means for circulating air from the outside and thence through material falling in said separating chamber with such air passing upwardly through said passage.

6. In particle separating apparatus; casing structure with walls defining a separating chamber that is round in cross section about an upright axis, an upright passage substantially in alignment with said axis extending upwardly from said chamber, and an approximately cylindrical fan chamber disposed above and connecting with the upper end of said passage with said passage extending axially into the bottom of said fan chamber; an outlet for said fan chamber in the circumferential periphery thereof; means for feeding particles to an upper portion of said separating chamber with the particles descending downwardly therefrom into said chamber; means for directing an air stream inwardly through the descending particles; n powendriven fan mounted within said fan chamber and constructed to draw air upwardly from said separating chamber and through said passage and expel it out through said outlet; an air inlet in the top of said fan chamber and valve means for controlling the flow of air through said inlet, and valve means in the path of air flowing from said passage to said fan chamber for controlling the flow of such air.

7. Particle separating apparatus comprising a casing with walls defining a first and a second fan chamber, a motor-driven fan in each of said fan chambers, means defining an inlet and an outlet for each fan chamber with such positioned so that on operation of the fan therein air is drawn in through the inlet and expelled through the outlet, a first separating chamber in communication with the inlet of said first fan chamber, means for effecting separation of particles into an air-suspendable and a nonair-suspendable fraction in said first separating chamber with the former fraction traveling from said separating chamber into said first fan chamber, a second separating chamber, conduit means connecting the outlet of said first fan chamber and said second separating chamber, and conduit means connecting said second separating chamber and the inlet of said second fan chamber, said second separating chamber being constructed so that on the flow of air and particles thereinto from said first fan chamber the particles are separated again into additional air-suspendable and nonairasuspendable fractions with the ai-r-suspendable fraction traveling into the conduit means connecting with said second fan chamber.

58. The particle separating apparatus of claim 7, wherep in conduit means connects the outlet of said second fan chamber with said first separating chamber.

9. Particle separating apparatus comprising upright casing structure with walls defining a first separating chamber and first and second fan chambers disposed one above the other in that order and in substantial vertical alignment, an elongated power d-riven shaft extending downwardly through the various chambers, fan mechanism connected to said shaft in each chamber operable to cause a circular movement of air therein about said shaft, an inlet for said first fan chamber at the base thereof and means connecting said inlet with said first separating chamber, a cyclone separator to one side of said casing structure, an outlet for said first fan chamber, means connecting said outlet with said cyclone sepanator, an inlet for said second fan chamber, means connecting said cyclone separator and the inlet of said second fan chamber, an outlet for said second fan chamber, and means connecting the outlet of said second fan chamber with said first separating chamber.

10*. In particle separating apparatus having a separating chamber, and means for producing a mixture of air and suspended particles within the separating chamber; casing structure with walls defining an upright passage connected at its lower end with said separating chamber, and an approximately cylindrical fan chamber disposed above and connecting with the upper end of said passage with said passage extending axially into the bottom oftsaid fan chamber; said fan chamber having an outlet in the circumferential periphery thereof; a power-driven fan mounted within said fan chamber and constructed to pull air upwardly from said separating chamber through said passage, and expel it through said outlet; valve means in the path of air flowing from said passage to said fan chamber for controlling the flow of such air; an air inlet for said fan chamber extending axially into the fan chamher; and valve means for controlling the vfiowof air through said air inlet,

References Cited in the file of this patent UNITED STATES PATENTS 826,772 Emerick July 24, 1906 1,978,802 Lissman Oct. 30, 1934 2,999,593 Stern Sept. 12, 1961 3,040,888 Hosokawa June 26, 1962 FOREIGN PATENTS 815,597 Great Britain July 1, 1959 

9. PARTICLE SEPARATING APPARATUS COMPRISING UPRIGHT CASING STRUCTURE WITH WALLS DEFINING A FIRST SEPARATING CHAMBER AND FIRST AND SECOND FAN CHAMBERS DISPOSED ONE ABOVE THE OTHER IN THAT ORDER AND IS SUBSTANTIAL VERTICAL ALIGNMENT, AN ELONGATED POWER-DRIVEN SHAFT ENTENDING DOWNWARDLY THROUGH THE VARIOUS CHAMBERS, FAN MECHANISM CONNECTED TO SAID SHAFT IN EACH CHAMBER OPERABLE TO CAUSE A CIRCULAR MOVEMENT OF AIR THEREIN ABOUT SAID SHAFT, AN INLET FOR SAID FIRST FAN CHAMBER AT THE BASE THEREOF AND MEANS CONNECTING SAID INLET WITH SAID FIRST SEPARATING CHAMBER, A CYCLONE SEPARATOR TO ONE SIDE OF SAID CASING 